Grieg Seafood was one of the first companies to look at the advantages of stocking post smolt to sea. In 2011 they decided to build their first saltwater based post smolt RAS in Finmark. This development consisted of 3 separate units with a total feeding capacity of 6,200 kg per day and were in operation in the summer of 2012.
These 3 post smolt RAS have since the start been a success. IAA’s Clearwater MBBR, a further development of the MBBR concept, has shown an un-precedented level of stability and high performance.
In saltwater RAS, there are certain challenges in that saltwater contains natural occurring high Sulphate concentrations (2700 mg/L). This, in connection with bio filters that are intended for sludge entrapment, poses a real risk of Sulphate Reducing Bacteria (SRB) activity with possibility of Sulphide formation. Sulphur Reducing Bacteria need sludge as a substrate. In an IAA Clearwater MBBR there are no possibilities of sludge deposits. Likewise, the IAA RAS design ensures that there are no possibilities of solids deposits or settlements anywhere else in the plant. This was high on Grieg Seafood’s list in relation to choice of RAS partner.
The 2 new post smolt RAS will be built in Trosnavåg, Rogaland. A challenge in this project is a limited area available. IAA has long been working on optimizing/reducing costly concrete structures and piping in our RAS design, which for this project also has borne fruit.
The 2 post smolt RAS will each consist of 2,500 m3 tank volume and a daily feeding capacity of 3,000 kg. The project will be completed by July 2017.